1. Field of the Invention
The invention is directed to an arrangement for switching on tariff levels with independent parameters, particularly in the form of different base amounts, by means of operating keys of an electronic taximeter.
2. Description of Related Art
A taximeter device is used, as known, for calculating fares from the services that ae furnished by the taxi vehicle on the basis of a driving commission. In order to determine a fare which is extensively appropriate to the service, it is necessary to design a tariff structure which takes into account, as far as possible, all circumstances that occur and which is based on the application of highly subdividable parameters. Thus, there are requirements, particularly in an electronic taximeter, to introduce an almost unlimited diversification into the fare calculation procedure from the elements making up the fare calculation as distance and time portions. Nevertheless, certain basic features from the epoch of mechanical taximeters are still contained in the structure of the tariff system. Accordingly, the use of four different tariff or tax levels was adopted in the introduction of most electronic taximeters and supplemented by expansion capabilities brought about through technology. Whereas in the mechanical devices it is still usually a matter of selecting the four tariff levels in a stepwise manner by means of a mechanical selector shaft or selecting each tariff individually by means of separate operating keys accompanied by switching on measures which block manipulation through the operator part, it is possible with the devices which are technologically constructed with microprocessors, to structure the tariff selection at a comparably lower cost by assigning permanently selected parameters. Accordingly, it has proved advantageous, with respect to expenditure on operating elements, to have a sequential selection of tariff levels in taximeters with a plurality of tariff levels. For operation, in standard taxi operation essentially two tariff selecting keys T1 and T2 are provided, by means of which the available tariff levels are selectable in dependence on a program sequence stored in an internal memory (ROM) for controlling the taximeter functions. In a standard programming of the taximeter, for example, the tariff selecting key T1 is assigned a switching sequence by means of which, through a kind of forward switching, the taximeter is switchable in a sequence through the tariff levels I to IV from a "FREE" state to "CASHIER" and "FREE". The second tariff selecting key T2 makes possible a reverse switching within the tariff levels IV to I in a standard programming in the OCCUPIED state. As known, a permanently determined so-called "base amount" is displayed immediately when the taximeter is turned on, in agreement with the tariff structure. As long as there were no large parameter differences in the individual tariff levels, i.e., as long as identical base amounts appeared in the display, in particular, the selection of a tariff level was unproblematic with respect to the "number games" on the fare display. With the increasing prevalence of larger parameter differences, such as various base amounts in the individual tax levels, differences between the initial distances covered and increment distance ratios, as well as differences in the control functions assigned to the tax level, misinterpretations of the fare and overlapping of functions in the tariff level selection can occur. For example, when the taximeter is changed from the "FREE" position to the tax level "III", wherein different base amounts are preset in the tax levels I, II and III, a different amount, which often increases by large steps, appears on the fare display during each selecting step. This display behavior can lead to misunderstandings on the part of the passenger, although the device is being operated in accordance with regulations.
The device behaves in a comparable manner when the rest of the parameters are applied. The calculation of automatic counters, for example, such as are used for the automatic tariff switchovers of "n" forward switchings, can run incorrectly when values are given for the desired function which are incompatible for the automatic counters in the tax levels which are to be skipped over during selection, for example, when changing from tax level I to tax level IV by means of actuating the operating key.
It is the object of the invention to provide a switching arrangement for the operation of the tariff level selection, by means of which the selected tariff level is identifiable in the display at all times and ambiguities in the fare display, during a tariff level selection process and overlapping of functions with respect to the tariff parameters in the individual tariff levels during the tariff level selection, are prevented.